Gopher made distributed Internet information feel like one navigable hierarchy of menus, growing rapidly alongside the early Web before hypertext, browser innovation, and changing economics pushed it aside.
ARPANET linked research computers through packet-switching nodes, created a community for network protocols, and provided the experimental environment from which Internet architecture emerged.
TCP/IP solved a different problem from ARPANET: how to connect multiple independent networks without forcing them to share one internal design.
Ray Tomlinson's ARPANET mail experiment joined local mailbox software with network file transfer and established the user@host addressing convention that became a universal symbol of online identity.
Packet switching replaced the idea of reserving one continuous circuit with a network that could divide data into independently routed packets, a foundation of modern digital networking.